1. Field of the Invention
The present invention relates to an apparatus and a method for feeding a wire in a treatment liquid contained in a liquid bath, particularly in an electrodeposition liquid bath for providing an insulating film on an outer peripheral surface of a wire like an electrical conductor. The apparatus can provide a constant appropriate tensile force to the wire without looseness so that the wire receives no excessive force to be reliably fed in the liquid with no damage of the wire.
2. Related Art
A known conventional method passes a wire like an electrical conductor in an electrodeposition liquid bath filled with an electrodeposition liquid for providing an insulating film on an outer peripheral surface of the conductor.
In the method, the wire is supplied from a supply unit having a wire winding bobbin and is cleaned to eliminate dust and contaminants therefrom. Then, the wire passes through a direction changing means to orient the wire toward the electrodeposition liquid bath filled with the electrodeposition liquid bath before the wire passes in the electrodeposition liquid bath for providing an insulating film on an outer peripheral surface of the wire.
Generally, a rolling support such as a roller or a pulley is used for continuously feeding a wire, for making some treatment on the wire, for moving the wire, and for changing the orientation of the wire.
FIGS. 3 to 5 show a conventional wire feeding method employing rolling supports to function as a wire guiding means.
The method uses an upper roller a rotated by a driving motor and a lower roller c disposed to be opposed to the upper roller a. The lower roller c contacts the roller a so as to be rotated with the rotation of the upper roller a. The roller a has a channel b formed in an outer circumferential surface thereof to receive a wire w such as an electrical conductor.
The motor rotates the upper roller a, which in turn rotates the lower roller c contacting the upper roller c, so that the wire w received in the channel b of the upper roller a is moved forward.
FIGS. 6 to 8 show another conventional wire feeding method employing rollers as rolling supports. The method uses an upper roller a′ rotated by a driving motor and a lower roller c′ disposed to be opposed to the upper roller a′. The lower roller c′ contacts the upper roller a′ so as to be rotated with the rotation of the upper roller a. The roller a′ has a channel b′ formed in an outer circumferential surface thereof to receive a wire w such as an electrical conductor. The lower roller c′ has a circumferential projection d′ formed on an outer surface thereof so as to be partially received in the channel b′.
The motor rotates the upper roller a′, which in turn rotates the lower roller c′ contacting the upper roller a′, so that the wire w is received between the channel b′ of the upper roller a′ and the circumferential projection d′ of the lower roller c′.
FIGS. 9 to 11 show further another conventional wire feeding method employing rollers as rolling supports. The method uses an upper gear a″ rotated by a driving motor and a lower gear c″ disposed to be opposed to the upper gear a″. The lower gear c″ engages with the upper gear a″ so as to be rotated with the rotation of the upper gear a″. The upper gear a″ has a channel b″ formed in an outer circumferential surface thereof to receive a wire w such as an electrical conductor. The motor rotates the upper gear a″, which in turn rotates the lower gear c″ engaged with the upper gear a″, so that the wire w is received in the channel b″ of the upper gear a″ so as to be moved forward.
In the conventional wire feeding methods employing the rolling supports of FIGS. 3 to 11, driving forces of the motors forcedly rotate the upper rollers a, a′ and the lower rollers c, c′ or the gear a″ and the gear c″ to reduce a larger tensile force which would be otherwise exerted on the wire w due to a long feeding distance or due to the orientation change of the wire w.
Furthermore, when the wire w is moved forward in a liquid such as an electrodeposition liquid, the wire feeding force needs to be intentionally adjusted according to the viscosity of the liquid, the feed speed of the wire, and the orientation change of the wire.
However, in the conventional wire feeding method employing the rolling supports of FIGS. 3 to 5, the tensile force of the wire is released to have a looseness when the motor stops its rotation. Thereby, the wire w may not be automatically set at a correct position relative to the rollers a and c when the motor restarts the operation, resulted in an disadvantage that the wire can not be moved forward immediately due to the disengagement of the wire w from the channel b of the roller a.
In the conventional wire feeding method employing the rolling supports of FIGS. 6 to 8, when the wire has a larger diameter, the wire may possibly disengage from the channel b′ so that the wire w is disadvantageously jammed between the upper roller a′ and the lower roller c′. This causes damage or breaking of the wire.
In the conventional wire feeding method employing the rolling supports of FIGS. 9 to 11, the upper gear a″ engages with the lower gear c″. Thus, when the wire w is disengaged from the channel b″, the wire is jammed between the teeth of the gears, disadvantageously causing damage or breaking of the wire.
In view of the disadvantages of the aforementioned conventional wire feeding methods, an object of the invention is to provide an apparatus and a method for feeding a wire in a treatment liquid, which provides a constant appropriate tensile force to the wire without looseness of the wire during a pause of the apparatus. The apparatus can correctly feed the wire without disengagement of the wire from a predetermined feeding path not to exert an excessive force on the wire to cause no damage of the wire. The apparatus also enables a continuos feeding of the wire with no damage thereof, enabling an improved workability, an easy replacement of parts, an easy maintenance, a simple construction, and an easy manufacturing and assembling thereof with a reduced cost.